Fur patches can be bought in flyshops, but there are many other sources for good fur - from furriers to roadkill.

When I'm talking fur and skin I'm talking flat pieces of pelt, and not masks or tails, which demand different considerations. I might return to that.
Skins like rabbit, opossum, mink, nutria, fox and many, many more can be a very good way of getting hair for all kinds of applications from tails and wings over dubbing to zonker strips. Skins are often much less expensive than the pre-cut strips or packaged dubbing, and having a skin opens for several uses, while the zonker strips or the dubbing have their limited uses.

Out of the bag

When buying a full skin or a piece of skin, make sure you can get it out of the bag to inspect both front and back. You are looking for consistent hair length and direction without any bald spots, and a skin side with no holes or tears. Depending on your use, you may want cured, softened skin, which is usually best if it's thin and has an even thickness.
Many times you will find a very inconsistent skin thickness with thin and fragile skin some places and stiff and thick skin on others. If you are cutting off hair for wings or raking it off for dubbing, that doesn't matter much, but for cutting zonker strips, you want suitably thin and uniform skin with consistent hair coverage. Too thick and it's both hard to cut and to get to look nice on the finished fly. Too thin and it's hard to work with and breaks easily - both while tying and when fished.

Well used nutria

Martin Joergensen

Cured or dried

Skins of course have to be prepared in some way. The most common ways are simply drying the skin or curing it through a way more complex chemical process. Drying requires that the fat and meat residues are removed and the skin is then mounted flat and dried, oftentimes after having been covered in borax or salt. Skin prepared in this way keeps fine, but comes out stiff like cardboard, and can only be used to cut or scrape off the hairs and not using the skin itself.
If the skin - the leather - is to be incorporated in the fly, mostly in the form of a strip, you will need a cured skin, where the leather side ends up soft and pliable. This is the most common way to find commercially prepared skins. Cured skins are not all created equal and as mentioned above you want suitably thin and uniform skin with no holes, scars or blemishes.

Natural and dyed

Cured skin comes in natural colors as well as dyed, and if you look at rabbit, the color selection nothing less than colossal. Most rabbit skins will be very consistently dyed and are typically clean and will have a nice and soft leather back. This is mainly because much of it is made for the clothing industry and not for fly tying, and the tailors are obviously much more picky than us fly tyers. That is also why it makes very good sense to buy your skin and fur from a furrier where you will often find the best quality and even the lowest prices.
Other types of skin like fox, mink, nutria (coypu), squirrel and many more are typically found in natural colors. Still they are commonly found in useful fly-tying colors, and many natural patches will have several different colors on one piece and hairs that are striated or black or white tipped.
Many of the newer fly-tying suppliers such as Foxy Tails, FutureFly, Pro Sportfisher, Eumer and others have a large selection of varying furs, natural and dyed, which are very well suited to fly-tying and with furs found in the exact colors needed for salmon flies in particular.
Personally I still find my best skin treasures by visiting furriers, sewing or hobby shops. You typically get more and better fur for less money, and going for grab bags or going through bins with scraps can reveal some surprisingly good pieces for next to nothing. They may be useless for sewing, but can be very useful for fly tying.

Mink skins

Martin Joergensen

Futurefly skins

Martin Joergensen

Length and texture

The hair varies in several ways apart from color, but the main concerns for the fly-tyer are length and texture (stiffness and shininess). The composition of underfur and guard hairs is also interesting. For some applications you remove the guard hairs for others part of the underfur.
Many skin types have soft, dense and frizzy underfur and spread out shiny and spiky guard hairs, very obvious in fur like mink. Other types of fur have less distinction between underfur and guard hairs with the difference being more alike and the transition between the two being less obvious. This is often the case in rabbit fur. Some furs have no separate layers like sheep in the large department and mole in the small, while some have almost no underfur with some seal furs as an example. Seals have fat under the skin doing the insulating job normally done by a dense underfur.
Some skin patches come with the spiky guard hairs shaven off and look more like sheep skin in miniature.

Scavenging from clothes

Mink stole

Martin Joergensen

If you go into thrift store or look at garage sales and such place, you will often bump into fur - from full fur coats to collars and trims. Some of it is dirty and worn and not really attractive, but sometimes you will find fur that's both nice looking and useful.
When buying fur in this form, you have one major problem: you can't see the backside. The reason that this is a problem, is that much fur used in clothing is cut into smaller pieces or even narrow strips and sewn back together, so the skin is cut and can't be used for strips as it's the case with cured skins. So when buying clothes, count on using the hairs off the skin for classic hair wings and dubbing. But that said, you should still have your eyes scanning for fur on clothes. Because you can make some great bargains.

The usual mantra

Of course the usual mantra has to come: you are looking for clean, consistent and non-smelly or greasy material. This is seen (and smelled) with the material out of the bag, and any grease, fat or dirt left in the hair or on the skin should have you put it back in the bag and hang it on the peg where you found it. One exception can be if it's really cheap, because if that's the case it might be worth buying and bringing home to a thorough wash, rinse and drying process.

One other exception is dried skins, which are sometimes available, and often very inexpensive, but worth considering. Dried skin is stiff as cardboard and not suitable for strips or wings that require soft skin. But for dubbing, tails and hair wings the dried skins can be more than adequate. Dried skin is also sometimes quite dirty or even greasy, which is not as big an issue as when you use the skin. You can soak the skin, scrape off the worst dirt and wash and dry it. This will often give a pretty good result, but with some risk of the skin curling up if you don't stretch it and peg it down to a board while it dries.

Making your own

If you know people who hunt, you can acquire great hair materials in the form of skins from their kills. Most of the animals are skinned, either right after the animal has been shot or when it's prepared to be cooked. The skin is very often trashed or simply left in the field, so it's usually easy to get your hands on for free.
Some animals like foxes or moles are not killed to be eaten, so there you might have to skin them yourself, but it can be worth the effort, and can supply you with material for ages of tying.
Once you have the skin in house, you need to start scraping and preparing it as fast as possible. As with hen and duck skins, it's a question of cleaning off fat and meat and drying them, using salt or borax, pegging them to a board for drying flat and washing them to get the hair ready for tying. Skins from larger animals such as deer and foxes can be cut into smaller and more regular shapes before the process is started, while smaller skins like hares, ferrets, rabbits, squirrels and others can be handled whole.

Dead squirrel

Martin Joergensen

You can also cure the skin, but getting the quality that's known from commercially available skins is difficult, but not impossible.
Roadkill is another source for skins, but make sure that the animal isn't too molested or too dirty and be prepared for some pretty smelly and dirty work if you embark on skinning roadkill unless it's very fresh. A good and easy use of roadkill like fox, racoon or squirrel can be just taking the tail. Cutting open the tail, removing the largest bones and simply drying it can be an easy way of getting very useful materials for tying. Again, use borax or salt to get it thoroughly dry.
No matter what you do, make sure you wash out and kill all bugs using water and soap, freezing or various chemicals.

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